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Accuracy of Measuring Trailer Tongue Weight Using Bathroom Scale Method


Tongue weight measured at the trailer jack will be different that weight measured at the the hitch. Is there a correction factor depending on how far back the jack is from the hitch center? I measure tongue weight using the bathroom scale/beam method. It takes a few minutes to set up but is much less expensive, requiring a bathroom scale, 2x6 about 6 feet long, and a couple of 6inch lengths of 1 1/4 inch angle iron to support the beam at each end. For my trailer I use a total length of 6, with one piece of angle supporting the beam 1 foot to left of hitch and the second piece on the scale 5 feet from the hitch on the other side, per eTrailer piece on doing this measurement. I use the trailer jack and a piece of pipe to level the trailer with the pipe 1 foot from the left end. I notice that the beam bends a little and wonder how this might affect the reading. Do you know if a rigid beam is important? On my Lance 1685 the scale reading is 94 pounds, which multiplied x 6 gives 564 pounds. Right in the range for a 5000 GTW trailer 10-15 of trailer weight. Note that this tongue weight exceeds the weight bearing hitch rating for many if not most trucks, including my 3/4 ton 2008 F350 Super Duty super cab diesel 4WD. Most trucks would require a weight distribution hitch to pull this trailer a surprise for me since most have hitch weight rating of 500 pounds for a weight bearing hitch. There are exceptions with some makers having much more robust weight bearing ratings. See ratings for 2013 trucks at ProPickup website. Storage is mostly upfront in the trailer, except for wardrobes at the back, and fresh water tank is in front of the axel. By the time I fill the water tank often camp in areas with no water, camping gear, generator, 2 propane tanks, 2 series 27 batteries on the tongue, bike rack on the receiver and bikes and 100 pounds of weight in the truck bed behind the rear axel, food etc I calculate/measure a hitch weight of about 1000 Pounds for a weight distributing hitch and 1000-100 lbs of weight in truck bed =900 pounds for a weight bearing hitch. Tongue weight will thus vary over about 450 pounds depending on gear and water carried. Wow. What an eye opener. This is a major liability issue in the event of an accident. I am told they will weigh your trailer and you can be sued if you exceed hitch ratings. So I bought the Reese 12,000 lb rated WD hitch that is rated adjustable from 600-1000 pounds because of the ease of adjustment compared to other trunion style hitches such as the Fastway that have some inherent sway control that dont have adjustable chains. I lose sway control on the Reese unless I add it on, but dont think sway is an issue with this 20 foot trailer on my 22 foot heavy truck. Comments?


Expert Reply:

The most accurate method to determine your tongue weight is to use a commercial scale at either a truck stop or quarry for example. The linked article details how to do this. You may have to pay a small fee for this service but it will provide a more accurate tongue weight measurement than the bathroom scale method. (Sag in the 2 x 4 used with the bathroom scale method will not have much effect on the tongue weight reading, nor will there be much difference between measurements taken at the hitch ball versus the tongue jack. There is no standardized correction factor for this variance.)

According to my research on the Ford website the 2008 F-350 Super Cab has a maximum towing capacity of 15,700-lbs for single rear wheel models and 16,000-lbs for dual rear wheel models.

The hitches we offer for your 2008 Ford F-350 Super Duty include three weight classes: Class III (rated for 1000-lbs maximum tongue weight when used with weight distribution), Class IV (rated for 1200-lbs maximum tongue weight when used with weight distribution) and Class V (rated for 2550-lbs maximum tongue weight when used with weight distribution). The link provided will show you all hitches we offer. The linked article covers hitch classes and capacities. You can check the safety/warning sticker on your hitch; it will indicate the maximum allowable tongue weight when used with a weight distribution system. Your trailer hitch receiver tongue and towing weight ratings should never be exceeded.

If your loaded and unloaded trailer weights vary widely (you indicate 450-lbs difference between loaded an unloaded states) you can remove the spring bars when your trailer is unloaded. If the ride of the unloaded trailer is unsatisfactory with the weight distribution system in place there is no reason that you cannot simply remove the bars.

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